The Emerging Layered Hydroxide Plates with Record Thickness for Enhanced High-mass-loading Energy Storage.

The past decade has witnessed the development of layered hydroxide-based self-supporting electrodes, but the low active mass ratio impedes its all-around energy storage applications. Herein, we break the intrinsic limit of layered hydroxides by engineering F-substituted β-Ni(OH) 2 (Ni-F-OH) plates with a sub-micron thickness (over 700 nm), producing a super-high mass loading of 29.8 mg cm -2 on the carbon substrate. Theoretical calculation and X-ray absorption spectroscopy analysis demonstrate that Ni-F-OH shares the β-Ni(OH) 2 -like structure with slightly tuned lattice parameters. More interestingly, the synergy modulation of NH 4 + and F - is found to serve as the key enabler to tailor these sub-micron-thickness 2D plates thanks to the modification effects on the (001) plane surface energy and local OH - concentration. Guided by this mechanism, we further develop the superstructures of bimetallic hydroxides and their derivatives, manifesting they are a versatile family with great promise. The tailored ultra-thick phosphide superstructure achieves a super-high specific capacity of 7144 mC cm -2 and a superior rate capability (79% at 100 mA cm -2 ). This work highlights a multiscale understanding of how exceptional structure modulation happens in low-dimensional layered materials. The as-built unique methodology and mechanisms will boost the development of advanced materials to better meet future energy demands. This article is protected by copyright. All rights reserved.